EP1726513A1

EP1726513A1 - Driving assistance system for lane keeping support, for lane change assistance, and for driver status monitoring for a vehicle

Info

Publication number: EP1726513A1
Application number: EP06113299A
Authority: EP
Inventors: Mauro Montiglio; Vincenzo Murdocco; Ludovico Consano; Pier Claudio Antonello
Original assignee: Iveco SpA
Current assignee: Iveco SpA
Priority date: 2005-05-02
Filing date: 2006-04-28
Publication date: 2006-11-29
Anticipated expiration: 2026-04-28
Also published as: EP1726513B2; ES2476995T5; ES2476995T3; EP1726513B1; ITMI20050788A1

Abstract

Described herein is a driving assistance system for vehicles, which operates both during normal driving in a given lane and during lane-change manoeuvres. The system comprises a lane-keeping-support module (LKSM), a lane-change-assistance module (LCAM), a driver-state-monitoring module (DSMM), and a decision module (DCM), which is responsible for all the decisions taken by the system both in the form of warnings and in the form of active interventions. In the case of situations of risk of involuntary exit from the lane, or of risk of lateral collision in lane-change manoeuvres, or of distraction from driving on the part of the driver, the system intervenes by applying an active steering torque to the vehicle or by intervening on some on-board systems or by supplying appropriate warning signals.

Description

The present invention relates to a driving assistance system for vehicles and more in particular to a driving assistance system for vehicles both during normal driving along a reference lane and during lane-change manoeuvres.
Driving assistance systems for vehicles are known in the art.
For example, the patents Nos. EP-1336550 and EP-806336 describe driving assistance systems for vehicles, designed to prevent involuntary exit from a traffic lane, due for example to lack of attention of the driver. Said systems can intervene by applying an active torque to the device for steering control, in order to suggest to the driver the appropriate corrective action.
The patent No. EP-1312506 , instead, describes a driving assistance system designed to assist the driver in lane-change manoeuvres by warning of potential danger, for example vehicles that are approaching in the adjacent traffic lanes, with which the assisted vehicle could come into collision during the lane-change manoeuvre.
Said known solutions, which will be described in greater detail in the following, afford limited levels of assistance to driving and hence are insufficient to guarantee a complete assistance in all risky driving situations.
Consequently, the purpose of the present invention is to indicate a complete driving assistance system for vehicles obtained by means of implementation of a decision control module (DCM), namely a system for assisting the driver of a vehicle both during normal driving along a given lane, and during lane-change manoeuvres, in which the assistance can be supplied by applying a given steering torque, which is processed, when the vehicle is proceeding along a certain lane, by means of a lane-keeping-support module (LKSM), which processes the information coming from a lane-tracking system (LTS) based upon a front video camera, whilst in the case of lane-change manoeuvres, the assistance is supplied by means of a lane-change-assistance module (LCAM), which processes the information coming from a lateral-lane-monitoring system (LLMS) based upon a video camera facing the lateral lane.
Furthermore, in order to improve the effectiveness and functionality of the system, this can be extended by means of a driver-status-monitoring module (DSMM), which processes the information coming from a driver-eye-monitoring system (DEMS) inside the cab or the passenger compartment, which frames the eyes of the driver, detecting the direction of his glance in order to recognize the state of drowsiness or distraction of the driver so that the decision module DCM of the driving assistance system will be able to implement different types of intervention, for example automatically activate the function of aid to lane-keeping (LKSM). Instead, when it is necessary, the system can automatically deactivate other systems, such as for example adaptive control of the cruising speed (adaptive cruise control - ACC).
Preferably, the lane-keeping-support module (LKSM) can prevent unintended deviations of the vehicle from the lane of travel by supplying an appropriate steering intervention, which enables the driver to correct the path of the vehicle when there is detected an imminent exit from the traffic lane, whereas the lane-change-assistance module (LCAM) enables prevention of the condition of emergency generated by the approach of another vehicle along the lane, towards which the vehicle performing the lane change is moving, by means of an appropriate steering intervention, i.e., by applying an active steering torque that inhibits the driver from performing a lane-change manoeuvre in dangerous conditions.
The active steering torque is preferably applied by means of electronic-control steering systems, and, for applications on heavy lorries, is preferably supplied by a servo electric power-steering unit (EPS) coupled to a servo hydraulic power-steering unit (HPS).
A particular subject of the present invention is a driving assistance system for vehicles as described in greater detail in the annexed claims, which form an integral part of the present description.
The purposes and advantages of the present invention will emerge clearly from the ensuing detailed description of an example of embodiment thereof (and of its variants) and from the annexed plate of drawings, which is provided purely by way of explanatory and non-limiting example and in which:

Figure 1 represents a block diagram of the driving assistance system forming the subject of the present invention;
Figure 2 represents a functional block diagram of the lane-keeping-support module LKSM;
Figure 3 illustrates a block diagram of the electrical/electronic and mechanical architecture of the system LKS;
Figure 4 illustrates the operative flow of the module LKSM;
Figure 5 illustrates the input and output variables of the algorithm of the module LKSM;
Figure 6 illustrates a functional block diagram of the module DSMM;
Figure 7 illustrates a diagram of the field of vision typical of the module LCAM;
Figure 8 illustrates an example of a rearview mirror modified in accordance with the invention;
Figure 9 illustrates a functional block diagram of the module LCAM; and
Figure 10 illustrates a functional block diagram of the decision control module DCM.

The same reference numbers and wordings in the various figures identify the same components or functionally equivalent components, elements or quantities.
The system forming the subject of the invention is now described in detail with reference to its principal constituent modules.

Lane-keeping-support module LKSM

With reference to Figures 1 and 2, the lane-keeping-support module LKSM performs the function of providing assistance to the driver so as to prevent involuntary lane change due for example to lack of attention, i.e., distraction or drowsiness on the part of the driver. This part of the system is strictly integrated with the other two modules of the system, i.e., the lane-change assistance module LCAM and the driver-state-monitoring module DSMM.
The main aim of the module LKSM is to provide assistance for lane keeping, by supplying a torque-request signal TR to the decision control module DCM, on the basis of one or more of the following criteria:

using the information on the instantaneous position and direction of the vehicle regarding the lane markings, or the road borders, detected by a lane-tracking system LTS, which processes images supplied by a front camera, preferably installed within the cab behind the area of the windscreen swept by the windscreen wipers;
using sensors for detecting activation of the direction indicators;
processing the information referred to above so as to calculate an appropriate active torque to be applied by means of a steering actuator when the signals issued by the system LTS indicate that the vehicle is about to leave the lane and the direction indicators are not activated;
using the information coming from the module LCAM so as to establish whether a lane-change manoeuvre can be undertaken in a safe way; and
processing the information from the module LCAM and calculating an appropriate active torque to be applied by means of the steering actuator, thus inducing the driver to keep on the lane where he is travelling, even though the direction indicators have been activated, in the case where the module LCAM has detected a condition that is dangerous for the lane-change manoeuvre.

With reference to Figures 2 and 3, a steering-actuation unit SAU is preferably provided on commercial vehicles by means of an electrical power-steering unit EPS associated to the steering column S and coupled to a hydraulic power-steering unit HPS. The steering system includes an electric motor and sensor devices for supplying electrical signals of the steering angle AS and of the steering torque ST that the driver applies to the steering column. The reference SW designates the driver's steering wheel, and W designates the wheels that steer the vehicle.
In a known way, the vehicle has direction indicators DI, which can be activated in a selective way, for example by means of a manual lever, so as to indicate a change of direction. The direction-indicator device DI includes a sensor for supplying electrical signals that indicate whether the direction lights are activated or not. The sensor can be shared with other control systems installed on the vehicle.
The vehicle is equipped with a driving assistance system according to the invention, which includes a lane-tracking system LTS for supplying electrical signals that can be used to identify the instantaneous position and direction of the vehicle in relation to the lane markings, or the road borders, which limit laterally or define the lane or the road along which the vehicle is travelling. The system comprises a lane vision system VS, which includes a camera facing the road in front of the vehicle, in association with an electronic device for processing the images generated by the camera.
The driving assistance system moreover comprises a sensor VV for supplying electrical signals indicating the speed of the vehicle. Said sensor can be shared with other on-board systems.
A processing unit ECU of the driving assistance system forming the subject of the invention is connected to the steering-angle sensor AS, associated to the steering column S, to the direction-indicator sensor DI, to the lane-tracking system LTS, to the vehicle-speed sensor W, to the lateral-acceleration sensor and yaw-velocity sensor YS.
The processing unit ECU can, for example, be connected to these sensors by means of a communication network N, such as for example a network that operates with the CAN protocol.
The processing of the lane-keeping-support module LKSM can be performed by the main microprocessor in the decision control system ECU, in common with the modules LCAM and DSMM, but can be performed also by a separate microprocessor.
Sensors and transducers YS for measuring the lateral dynamics of the vehicle, comprising a lateral-acceleration sensor and a yaw-velocity sensor, are also connected to the processing unit by means of the network N. These sensors can be shared with other control systems installed on the vehicle.
The processing unit of the module LKSM controls the steering-actuation unit SAU in such a way as to apply an active torque of a given value to the steering actuator when the signals issued by the lane-tracking system LTS and by the other sensors indicate that the vehicle is about to leave the lane in which it is travelling and the direction indicators are not activated.
Similarly, when the module LCAM, described in the following, detects a dangerous situation, even though the direction indicators are activated, an active torque of a given value is applied to the steering actuator, by means of the processing unit, so as to induce the driver to keep on the same lane, thus preventing a dangerous lane change.
Application of this active torque gives the driver a sensation of resistance to the deviation from the lane in terms of a resisting torque on the steering wheel. The active torque likewise provides an intuitive indication of the steering action requested to get the vehicle to return within the limits of the desired lane.
On the other hand, the function performed by the module LKSM is disabled, albeit ready for use, if the driver activates a direction indicator with the deliberate intention of changing lane. Instead, the function is not disabled, even though the driver activates an indicator, when the module LCAM detects an imminent danger in lane change.
The processing unit calculates the radius of curvature of the portion of road on which the vehicle is travelling. This operation is performed using signals issued by the vision system VS. On the basis of this information, the unit ECU of the module LKSM calculates the active torque to be applied to the steering column S, on the basis of various methods, according to whether the portion of road along which the vehicle V is travelling is basically straight or curved.
The unit ECU can also be pre-arranged not only to analyse the signals issued by the vision system VS, which is able to recognize multiple lanes, also including the adjacent lanes, but also to receive information from a satellite global positioning system GPS, and process the information of the maps of the GPS system regarding the types of road along which the vehicle is travelling (motorway, trunk road, main and secondary roads, etc.) and the number of lanes. In this case, it is advantageous if the resisting torque that would have to be applied to the steering column S is calculated on the basis of a variety of methods, depending upon which lane the vehicle is travelling along (intermediate, left-hand, right-hand).
In each of these cases, the active torque that it would be necessary to apply on the steering column S is preferably calculated according to the transverse position and instantaneous direction of the vehicle within the traffic lane.
In calculating the value of active torque to be applied to the steering actuator, it is preferable to take into account at least one set of parameters comprising the speed of the vehicle, the yaw velocity and the transverse acceleration. For commercial vehicles it is preferable to take into account also the value of the load, and for heavy commercial vehicles it is preferable to take into account also the presence of a trailer or semitrailer. This information can be supplied by sensors shared with other control systems of the vehicle and accessible by means of a network operating, for example, with the CAN protocol.
It is also preferable if the active torque to be applied to the steering actuator is calculated according to the value of the maximum torque set by the driver using an interface SEL, such as for example a selector, a push-button or the like, to enable the driver to personalize the level of torque for intervention on the steering.
A further parameter that the processing unit can use for calculating the active steering torque is the camber of the portion of road on which the vehicle is travelling. The camber can be calculated on the basis of signals of transverse acceleration, or by means of an inclinometer IN, or by means of information coming from a satellite global positioning system GPS and an appropriate digital map provided with this detailed information. The flowchart of Figure 4 shows the logical sequence of the main operations carried out by the module LKSM. It may be noted that the module LKSM in the step 401 verifies whether an alarm of a "blind spot" type, described in the following, has been issued by the module LCAM, or whether, in step 402, a "state of distraction or drowsiness" alarm has been detected by the module DSMM. If no alarms have been issued, the system verifies, in step 403, the condition of "intention to change lane" of the driver, or more generally of leaving the lane on which he is travelling. This is done by verifying whether the direction indicators have been activated or not. Furthermore, the intention of the driver to change lane can also be identified by a system for monitoring the eyes and face of the driver DEMS (Figures 1 and 6), which is able to detect the direction of his glance, and in particular his glance when he is facing the rearview mirrors.
If the module LKSM recognizes that it is necessary to intervene in the case of intention not to change lane, then, in step 404, it selects a different strategy of control depending upon whether the vehicle is travelling along a rectilinear or a curved stretch of road. If the portion of road comprises a plurality of lanes, the system determines, in step 405 or step 406, in which lane the vehicle is travelling (for example, right-hand lane, left-hand lane or central lane), and then determines the torque to be applied to the steering wheel, in one of the corresponding steps from 407 to 412. Next, in step 413, it processes and sends to the module DCM (Figures 1 and 2) a request of active torque TR to be applied on the steering.
The active steering torque is calculated according to other parameters or values, such as:

instantaneous position and direction of the vehicle with respect to lane marking or road border signs detected;
speed of the vehicle;
radius of curvature of the lane;
camber of the portion of road on which the vehicle is travelling;
signals regarding the lateral dynamics of the vehicle, comprising yaw velocity and lateral acceleration;
mass of the load and presence of a trailer;
maximum active torque set by the driver for actuation of the steering unit;
instantaneous steering torque applied by the driver; and
number of lanes and information on the type of road on which the vehicle is travelling, if available by means of a navigation system.

Figure 5 shows the input and output variables of the algorithm for processing the active steering torque of the module LKSM.
In addition, the module LKSM processes the information regarding the presence of the hands of the driver on the steering wheel. The information that the driver has taken his hands off the steering wheel for a certain time can be used by the module DCM to generate a specific alarm for the driver.
The possibility of detecting the presence of hands on the steering wheel also enables an improvement in the strategies of actuation of active steering.
The above detection can be made from a comparison of the steering torque applied by the driver and its time derivative with an appropriate torque threshold value and torque-derivative threshold value, respectively. The absence of the hands from the steering wheel is detected in the case where the torque applied by the driver and its time derivative remain both simultaneously below the aforesaid threshold values for a certain pre-set period of time. Unlike the systems according to the prior art, in which the presence of the driver's hands on the steering wheel is recognized by sensors of various types (pressure sensors, contact sensors, optical sensors, etc.) set on the crown of the steering wheel, the invention is of simpler implementation and entails modest additional costs. Processing of the values of steering torque moreover enables recognition also that particular situations of danger have arisen, such as execution of emergency manoeuvres or sudden release of the steering wheel by the driver.
Finally, the module LKSM, on the basis of the information coming from the lane-tracking system LTS, processes information regarding the "driving style " of the driver, identifying improper behaviour, such as for example an excessively imprecise style of driving; said evaluation can be carried out, for example, by observing a frequent number of interventions of the LKS in a given time interval.

Driver-status-monitoring module DSMM

It is known that lack of attention, which comprises both distraction and drowsiness, is a common cause of accidents. The problem is normally classified as visual distraction or else cognitive distraction and drowsiness.
Visual distraction occurs, for instance, when the driver must read or write a long SMS message on the phone. Cognitive distraction may arise during an important telephone conversation, or if the driver is seriously involved in solving a problem. In both cases, the camera for the driver monitoring can detect when the level of lack of attention becomes dangerous. For example, the system can detect that the driver is busy too long or too often with the radio and is paying little attention to the road, or else that he is gazing in front of himself without really seeing, because for example he is mentally concentrating on a problem and his attention has been distracted from driving.
The state of the art of systems for monitoring driver drowsiness consists in supplying a signal warning of danger when a dangerous condition is detected. The danger warning may be acoustic or else supplied by vibration devices, for example, causing vibration of the seat, or else visual by means of LEDs, or else light icons, or messages flashing on the dashboard.
The subject of this part of the invention is a driver-status-monitoring module DSMM, which supervises lack of attention of the driver from his driving task, so as to supply to the decision module DCM a signal LAT regarding an evaluation of the level of attention of the driver. On the basis of said information, the module DCM can decide to intervene to recall the driver's attention or else to assist him by activating or deactivating other on-board systems. The purpose of the module DSMM is to prevent certain situations of danger caused by lack of attention, for example involuntary exit from the traffic lane or lane changes performed in conditions of danger due to the risk of collision with vehicles in adjacent lanes. The module DSMM is integrated with the other two modules LKSM and LCAM (Figure 1).
With reference to Figure 6, the module DSMM receives information from the system for monitoring the driver's eyes and face DEMS, which is able to follow the movements of the driver's eyes or the direction of his glance and blinking rate so as to detect drowsiness. On the basis of this information, the module can supply a danger signal if the driver is not paying sufficient attention to driving or can supply an alarm if it recognizes a state of drowsiness. The system is based upon a camera CAM1 inside the cab, which recognizes the movement of the driver's eyes.
In addition, the module DSMM receives other information (block ICB), for example available via a communication network (CAN network) of the vehicle, regarding the use of on-board devices, such as primary and secondary commands, navigation system, radio, telephone, computer, etc., which may distract the driver.
Whereas known methods for detecting the state of drowsiness of the driver are based only upon recognition of the duration of closing or frequency of blinking of the eyes, the system forming the subject of the invention integrates three different sources:

1) recognition of the direction of the face and of the glance;
2) information available on the CAN communication network of the vehicle, on which messages are available regarding the possible use of any on-board device; and
3) information coming from the lane-tracking system LTS, via the block LKSM, which can also be used for recognizing improper driving behaviour, such as an excessively imprecise style of driving, which can be detected by observing, for instance, the frequency of interventions of the LKSM, and comparing it with an
appropriate threshold value.

The advantage of this new approach is a more reliable and more complete recognition of the lack of attention of the driver. In particular, the information that derives from the lane-tracking system LTS, via the block LKSM, can provide a reliable evaluation on the driver's driving style, and hence recognize anomalous, improper or dangerous driving behaviour. On the other hand, the systems based only upon a telecamera for monitoring the driver can be insufficient in certain conditions, for example in difficult conditions of lighting of the cab or else when the driver is wearing spectacles.
Following upon detection by the module DSMM of a state of lack of attention, the decision control module DCM, as specified in greater detail in the following, can intervene both by generating acoustic or visual warnings of danger AVW, and by activating or deactivating other on-board systems, thus inducing the driver to recover his concentration on the task of driving.
In practice, the present driving assistance system can intervene with different modalities, as explained in greater detail hereinafter in the description of the decision control module DCM. This multiplicity of modalities of intervention constitutes a distinctive element of the present invention.

Lane-change-assistance module LCAM

The function of the module LCAM is to assist the driver in lane-change manoeuvres, by warning of risk conditions generated by the approach of another vehicle in the adjacent lane without the driver realizing it (alarm of a "blind spot" type, as mentioned previously), so as to prevent the driver from performing a lane-change manoeuvre in conditions of risk and hence preventing possible collision.
The module LCAM is functionally interfaced with the other two modules DSMM and LKSM.
In order to provide a lateral-lane-monitoring system, an external opto-electronic sensor is used, preferably integrated in the rearview mirror driver side, which supplies an output signal designed to detect the presence and movement of another vehicle in the adjacent lane and to detect the lateral movements of the vehicle with respect to the lane demarcation lines.
The area supervised by the opto-electronic sensor is illustrated in Figure 7, where also illustrated are the areas supervised by the rearview mirrors driver side of a heavy vehicle 71, namely a class-IV wide-angle mirror (area 72) and a class-II rearview mirror (area 73), as prescribed by the European directive 2003/97/EC.
With reference to Figure 8, a vehicle has an external rearview mirror 81 in which an opto-electronic sensor is incorporated consisting of a digital camera CAM2 82 in CMOS technology. The camera 82 may be integrated in the body of the mirror 83 or in its support 84. The camera has a field of vision defined by the area 74 of Figure 7, which has a wider field of vision than the conventional rearview mirrors, designated by 72 and 73 in the figure.
With reference to Figure 9, the module LCAM uses the information supplied by the lateral-lane-monitoring system LLMS and by the lane-tracking system LTS. After correlating this information with parameters regarding the dynamics of the vehicle, the module determines a signal LRC regarding a level of risk of lateral collision with possible vehicles in the overtaking lane and supplies it to the block DCM.
The module LCAM uses the following parameters:

position and direction of the vehicle with respect to the lane of travel L1;
presence and relative speed of another vehicle that is approaching on the adjacent lane L2;
longitudinal speed of the vehicle VV;
steering angle AS and steering angular velocity;
activation of the direction indicators DI; and
steering torque ST applied by the driver.

When the lateral-lane-monitoring system LLMS detects simultaneously a lateral approach of the vehicle to the lane marking M and also the approach of another vehicle along the adjacent lane L2, the module LCAM processes the level of risk of lateral collision and sends this information to the module DCM, which decides on the appropriate interventions, which range from a simple acoustic or visual warning to active intervention on the steering, according to the level of risk.
This device improves the driving safety as compared to what can be obtained using traditional rearview mirrors, which leave a part of the area at the side of the vehicle, the so-called blind angle, out of the field of vision. The device uses a video camera integrated in the rearview mirror as opto-electronic sensor, which, as compared to traditional rearview mirrors, achieves a better lateral monitoring in so far as it also carries out detection of obstacles and makes it possible an active intervention.
The module LCAM assists the lane-change manoeuvres, warning of the condition of risk generated by the approach of another vehicle along the same lane as the one into which the vehicle would move by changing lane, and has the following characteristics:

it is equipped with opto-electronic sensor means, for example a telecamera of a CMOS type, on the external rearview mirror of the vehicle;
it processes the signals issued by the sensors to detect a set of variables, amongst which the position of the vehicle with respect to the closest side of the lane of travel;
it processes the signals issued by the sensors to detect when a vehicle that is following is approaching on the lane adjacent to the one on which the vehicle is travelling; and
it determines the level of risk of collision with the vehicle in the adjacent lane.

The sensors typically consist of a digital video camera CAM2 preferably a colour one. The use of a colour video camera renders the signal stronger and improves the capacity of operating correctly in all environmental conditions to eliminate any disturbance due, for instance, to shadows of other surrounding objects. The current technology of digital cameras enables their integration in the rearview mirror of the vehicle or in any case in the body of the mirror or else on its support. A further advantage is that said electronic processing means may be completely digital. The device can be connected to the on-board network to simplify the electrical connections.
As a further degree of functionality, the electronic processing means may comprise various other functions such as, for example, warning of other vehicles that are overtaking the stationary vehicle or else warning of other vehicles that are overtaking at a low speed, for example, less than 25 km/h, or else detection of vehicles that are approaching from behind at night and automatic activation or deactivation of the vehicle lights.
The signals issued by the sensor CAM2 are supplied to the electronic processing circuit LLMS. The circuit executes a series of operations, such as, for example, estimation of the distance between the vehicle itself and a vehicle that is arriving behind, during overtaking. According to the invention, the electronic processing means LLMS are moreover able to estimate the lateral distance between the vehicle itself and the adjacent side M of the lane L1 on which the vehicle is travelling, by means of appropriate image processing.

Decision control module DCM

The modules LKSM, LCAM and DSMM described previously are integrated with a further module called decision control module (DCM), which has a higher hierarchical level and is responsible for all the decisions taken by the system, whether in the form of warnings or in the form of active interventions.
The decision control module DCM constitutes the heart of the driving assistance system and is responsible for all the possible interventions of the system, which can assume either the form of (acoustic and/or visual) warnings or the form of actuation of the steering system or of other on-board systems.
The module DCM is interfaced with the following modules described above:

module LKSM, from which it receives a request for active steering torque;
module LCAM, from which it receives an evaluation of the level of risk of lateral collision; and
module DSMM, from which it receives an evaluation of the level of attention of the driver.

Furthermore, since the module DCM is responsible for all the interventions of the driving assistance system, it contributes to determining operation of one or more of the following on-board systems, as shown in Figure 10:

active steering system SAU;
adaptive-cruise-control system ACC;
heating-ventilation-air-conditioning-control system HVAC;
electrical-safety-belt-pretensioning system SBP;
infotainment system (radio, hi-fi, handsfree-talking telephone, etc.) INF; and
acoustic-and-visual-warning devices AVW.

On the basis of the information received, in addition to being able to issue appropriate warning signals of an acoustic or visual nature, the module DCM can take the decision of activating or deactivating some on-board systems and in particular it can intervene by enabling or disabling the support supplied to the driver by the modules LKSM and LCAM, according to a series of pre-defined rules. By way of non-limiting example, listed in Table 1 below are some of the most important decisions of intervention that the module DCM can make to increase the level of vehicle safety.

For example, described in the first row of the table is the type of decision taken by the module DCM in the following situation: the module LKSM is not active, i.e., the function lane-keeping-support LKS has not been activated by the driver; the module LCAM has not detected any dangerous vehicle on the left-hand side, whereas the module DSMM warns of a state of distraction of the driver. In this case, the module DCM decides to activate the function LKS automatically and to display the message "Lane-keeping Support ON".

LKSM	LCAM	DSMM	Decision of the DCM
OFF	-	Distraction detected	LKS activated automatically. Displays message "Lane-keeping Support ON"
OFF	-	Fatigue detected	LKS activated. Assigns value Max to Torque LKS. Displays message "DROWSINESS Detected"
ON	-	Distraction detected	Assigns value Max to Torque LKS. Displays message "LKS Value Max"
ON	-	Fatigue detected	Assigns value Max to Torque LKS. Displays message "DROWSINESS Detected"
OFF	Vehicle on left side, low risk	-	Turns on Yellow LED
OFF	Vehicle on left side, medium risk	-	Turns on Red LED. Issues Acoustic warning
OFF	Vehicle on left side high risk	-	Turns on Red LED. Issues Acoustic warning. LKS activated automatically, sets max Torque.
...	...	...	...

In practice, the system is able to intervene by using a wide range of interventions in order to maintain the vehicle in safety conditions.
Given in what follows are some significant examples of possible interventions by the system:

generation of a combination of messages, icons or LEDs flashing on the dashboard as a warning;
intervention on the system ACC (if active), deactivating it in order to prevent any lowering of attention of the driver at the safety distance; alternatively, in order to guarantee maintenance of the highest safety condition, the system DCM can vary the "headway" value of the system ACC, temporarily increasing the safety distance to the maximum value;
intervention on the module LKSM in order to increase the level of intervention of the active steering torque to the maximum value. In this way, the driver can perceive the active steering torque better, in the case of involuntary exit from the lane or lane change in dangerous conditions;
automatic turning-off of the audio systems, such as radio or hi-fi devices or handsfree-talking telephone, or else lowering of the volume, thus reducing a possible source of distraction;
regulation of the air-conditioning system to a lower temperature, or else activation of the fan at a higher speed, to alert the driver on the risk of lack of attention; and
activation of the electrical safety-belt pretensioner SBP, so as to grip the driver more securely to the seat, preparing him for a possible impact and at the same time warning him of the risk of collision.

Of course, all the aforementioned interventions constitute just a few examples of the possible actions that the module DCM can undertake; other interventions of activation or deactivation can constitute countermeasures useful for increasing the level of safety, as the level of lack of attention detected varies.
The functions described above, provided by the lane-keeping-support module LKSM, lane-change-assistance module LCAM, driver-status-monitoring module DSMM, and decision control module DCM, can be obtained via computer programs, which can reside in one or more electronic processing units, for example of the types described above, integrated together or else distributed over a number of different co-operating units. Said computer programs comprise encoding means for implementing one or more steps of the functions described above, when these programs are run on a computer. Consequently, it is understood that the scope of protection of the present invention extends to said computer programs and moreover to computer-readable media, which comprise a stored message, said computer-readable media comprising program-encoding means for implementation of one or more steps of the functions described above, when said program is run on a computer.
Variant embodiments to the non-limiting example described herein are possible, without thereby departing from the sphere of protection of the present invention, including all the embodiments that for a person skilled in the branch are equivalent.
From the foregoing description the person skilled in the art is able to carry out the invention without introducing any further constructional details. In particular, implementation of the computer programs may be performed on the basis of programming languages which are in themselves known, of any type used in the field of application of the present invention.

Claims

Driving assistance system for vehicles both when travelling along a reference lane and during lane-change manoeuvres, said system comprising:
- a lane-keeping-support module (LKSM), which processes the information coming from a lane-tracking system (LTS), which comprises a front-vision system (VS) and is designed to supply signals indicating assistance when the vehicle is travelling along a lane;

- a lane-change-assistance module (LCAM), which processes the information coming from a lateral-lane-monitoring system (LLMS), which comprises a lateral-vision system (CAM2), and is designed to supply signals indicating assistance when the vehicle carries out lane-change manoeuvres; and

- a decision control module (DCM), which processes said signals that it receives from said lane-keeping-support module (LKSM) and lane-change-assistance module (LCAM), for applying an active steering torque, or for supplying warning signals in the case of onset of situations of emergency.
Driving assistance system for vehicles according to claim 1, characterized in that it moreover comprises a driver-status-monitoring module (DSMM), which processes information coming from a driver-monitoring system (DEMS), which comprises a vision system (CAM1) inside the cab of the vehicle, and is able to generate signals regarding conditions of drowsiness or distraction of the driver; said signals generated by said driver-status-monitoring module (DSMM) being supplied to said decision control module (DCM).
Driving assistance system for vehicles according to claim 1, characterized in that said lane-keeping-support module (LKSM) comprises means of processing able to determine said assistance when the vehicle is travelling along a lane, on the basis of one or more of the following criteria:
- using the information of the instantaneous position and direction of the vehicle with respect to the lane markings or to the road borders, detected by a lane-tracking system LTS, which processes images supplied by a front camera, preferably installed within the cab or passenger compartment behind the area of the windscreen swept by the windscreen wipers;

- using sensors for detecting activation of the direction indicators;

- processing the information referred to above so as to calculate an appropriate active torque to be applied by means of a steering actuator when the signals issued by the system LTS indicate that the vehicle is about to leave the lane and the direction indicators are not activated;

- using the information coming from the lane-change-assistance module (LCAM) so as to establish whether a lane-change manoeuvre can be undertaken in a safe way; and

- processing the information from the lane-change-assistance module (LCAM) and calculating an appropriate active torque applied by means of the steering actuator, thus assisting the driver to keep on the lane where the vehicle is travelling, even though the direction indicators have been activated, in the case where the lane-change-assistance module (LCAM) has detected a condition that is dangerous for the lane-change manoeuvre.
Driving assistance system for vehicles according to claim 3, characterized in that said lane-keeping-support module (LKSM) is able to receive information from a satellite global positioning system (GPS), regarding the types of road on which the vehicle is travelling (motorway, trunk road, country road, etc.) and the number of traffic lanes, said lane-keeping-support module (LKSM) comprising means for calculating said active torque to be applied by said steering-actuation unit (SAU) also on the basis of one or more of the following parameters:
- instantaneous position and direction of the vehicle with respect to lane marking or road border signs detected;

- speed of the vehicle;

- radius of curvature of the lane;

- camber of the portion of road on which the vehicle is travelling;

- signals regarding the lateral dynamics of the vehicle that comprise yaw velocity and lateral acceleration;

- weight of the load and presence of trailer;

- maximum active torque set by the driver for actuation of the steering unit;

- instantaneous steering torque applied by the driver; and

- number of lanes and information on the type of road on which the vehicle is travelling, if available, via navigation system.
Driving assistance system for vehicles according to claim 3, characterized in that said lane-keeping-support module (LKSM) moreover comprises means for processing information regarding the presence or absence of the hands of the driver on the steering wheel, supplied to said decision control module (DCM).
Driving assistance system for vehicles according to claim 5, characterized in that said information regarding the presence or absence of the hands of the driver on the steering wheel is derived from means for comparing a steering torque applied by the driver and its time derivative with a torque threshold value and a torque-derivative threshold value, respectively; the absence of the hands from the steering wheel being recognized in the case where the torque applied by the driver and its time derivative remain both simultaneously below said threshold values for a certain period of time.
Driving assistance system for vehicles according to claim 3, characterized in that said lane-keeping-support module (LKSM), comprises means for processing information regarding the "driving style" of the driver, on the basis of the information coming from the lane-tracking system (LTS), identifying improper behaviour, such as for example an excessively imprecise style of driving, depending on the number of interventions for lane keeping in a certain time interval.
Driving assistance system for vehicles according to claim 1, characterized in that said lane-change-assistance module (LCAM) comprises means for using the information supplied by said lateral-lane-monitoring system (LLMS) and by said lane-tracking system (LTS), for correlating said information with parameters regarding the dynamics of the vehicle, and if it detects a situation of danger it acts on a steering-actuation unit (SAU) and issues visual and acoustic warning signals, said parameters regarding the dynamics of the vehicle being one or more of the following:
- position and direction of the vehicle with respect to the lane of travel;

- presence and relative speed of another vehicle that is approaching on an adjacent lane;

- longitudinal speed of the vehicle;

- steering angle and angular steering velocity;

- activation of direction indicators; and

- steering torque applied by the driver;
said situation of danger being detected when there occurs a lateral approach of the vehicle to the lane marking (M) and also the approach of another vehicle along an adjacent lane.
Driving assistance system for vehicles according to claim 8, characterized in that said position of the vehicle with respect to the lane of travel comprises a lateral distance between the vehicle and said lane marking (M).
Driving assistance system for vehicles according to claim 8, characterized in that said lateral-vision system (CAM2) in said lane-change-assistance module (LCAM) comprises a digital colour video camera (CAM2) positioned in a rearview mirror driver side (71) or on its support.
Driving assistance system for vehicles according to claim 2, characterized in that said driver-status-monitoring module (DSMM) comprises means for integrating said information coming from a driver-monitoring system (DEMS) with information on the use of on-board devices available via messages on an internal communication network (CAN) and with information coming from said lane-tracking system (LTS), and for identifying improper behaviour, such as for instance an excessively imprecise way of driving, depending on the number of interventions for lane keeping in a certain time interval.
Driving assistance system for vehicles according to claim 2, characterized in that said decision control module (DCM) contributes to determining the operation of one or more of the following systems on board the vehicle:
- active steering system (SAU);

- adaptive-cruise-control system (ACC);

- heating-ventilation-air-conditioning-control system (HVAC);

- electrical-safety-belt-pretensioning system (SBP);

- infotainment system (INF); and

- acoustic-and-visual-warning devices (AVW).
Driving assistance system for vehicles according to claim 12, characterized in that said decision control module (DCM), comprises means for taking decisions of activating or deactivating on-board systems, on the basis of the information received, as well as means for determining intervention for enabling or disabling a support supplied to the driver by said lane-keeping-support module (LKSM) and lane-change-assistance module (LCAM).
Driving assistance system for vehicles according to claim 13, characterized in that said decision control module (DCM) comprises means for causing one or more of the following interventions:
- generation of a combination of messages, icons or LEDs flashing on a dashboard as a warning;

- intervention on said adaptive-cruise-control system (ACC), if active, deactivating it in order to prevent lowering of attention of the driver at the safety distance; or else in order to guarantee a condition of greater safety, varying a "headway" value of said adaptive-cruise-control system (ACC), increasing temporarily a safety distance to the maximum value;

- intervention on said lane-keeping-support module (LKSM) in order to increase to the maximum value the level of intervention of the active steering torque;

- automatic turning-off of the audio systems, such as radio or hi-fi devices or handsfree-talking telephone, or else lowering of the volume, of said infotainment system (INF);

- regulation of said heating-ventilation-air-conditioning-control system (HVAC) at a lower temperature, or else activation of a fan of said system at a higher speed; and

- activation of said electrical-safety-belt-pretensioning system (SBP) so as to grip the driver more securely to the seat and warn him of an imminent danger.
Computer program comprising program-encoding means able to carry out the functions of claims 1 to 14, when said program is run on a computer.
Computer-readable medium, comprising a recorded program, said computer-readable medium comprising program-encoding means able to carry out the functions of claims 1 to 14, when said program is run on a computer.